The present invention relates to a lifting/swiveling drive having a working element which can move rotatably and linearly relative to a housing element.
Lifting/swiveling drives of this type are known commercially and are customary in diverse forms and designs. They are used in different spheres essentially for carrying out an entirely determined lifting movement, for example of a tool, with a simultaneous or subsequent rotational movement in order to process a certain workpiece or, for example, to pick up a certain object and to deposit it at another location.
In the case of conventional lifting/swiveling drives, use is made, for example, of disk cam mechanisms which are subject to a high degree of wear and are thereby imprecise.
Furthermore, lifting/swiveling drives of this type are very slow in operation and can therefore only be used to a limited extent during production. For example, lifting/swiveling drives of this type are used in the production of compact disks (CDs) which, in order for the plastic carrier to be coated, have to be inserted into a corresponding device for this purpose. It should be possible for this insertion to take place very exactly, precisely and very rapidly. Manufacturing devices of this type are in operation 24 hours a day and require long service lives at high velocities. The precision is considerably impaired by wear, which is disadvantageous. The consequence of higher velocities is a higher degree of wear and a higher breakdown rate, which is undesirable.
Furthermore, lifting/swiveling drives of this type can be used, for example, as xe2x80x9cwafer handlingxe2x80x9d in the semiconductor industry.
DE 29 06 404 describes an electric motor which comprises stator and rotor parts together with bearing points. In this case, an armature and an induction motor as armature for a linear motor are arranged one behind the other on a common shaft. An induction motor part is provided as a synchronous motor with permanent induction armatures which are controlled with the aid of a sensor.
U.S. Pat. No. 5,952,744 discloses a lifting/swiveling drive having two independent coils for the rotative and linear driving of an actuating element. The measurement of the rotational movement, in particular of the swiveling movement, takes place in an optical manner by means of optical sensing elements.
According to U.S. Pat. No. 5,600,189, an electromagnetically operated actuator is described, in which a rotational movement takes place electromagnetically and a sliding movement takes place hydraulically. The measurement of the rotational movement takes place via a reference measurement of different signals, which is imprecise.
The present invention is based on the object of providing a lifting/swiveling drive of the type mentioned at the beginning which eliminates the above-mentioned disadvantages and with which, in particular, the precision, the velocities and accelerations of rotative and linear type are to be increased considerably accompanied by longer service lives.
Furthermore, a control of the linear and rotative movement of the working element is to be possible in a highly precise and exact manner.
This object is achieved in that in order for the working element to move in a controllable, linear and rotative manner relative to the housing element, at least one linear motor and at least one rotative motor are assigned to the working element and/or the housing element.
This object is achieved by the features of the present invention wherein a linear motor and a rotative motor are arranged spaced apart radially from each other in the housing element. The stators thereof are connected firmly and fixedly to the housing element and, in particular, to its inner cylinder wall. The housing element is preferably of cylindrical design and the working element is mounted in a linearly moveable and rotatable manner in it.
In the region of the linear motor and of the rotative motor, magnets are arranged on the outside of the working element, on the circumferential surface thereof, in a manner such that they at least partially encircle it radially. In this case, linear motor and rotative motor are in contactless connection with the respective magnets, in particular permanent magnets, of the working element.
The magnets are of a radial length which is greater than a length or an effective region of the rotative motor or of the linear motor.
This enables the working element to rotate in a contactless manner and independently either about a central axis as desired and also in any desired independent numbers of revolutions and at the same time to move linearly to and fro independently of this movement.
This enables any desired tool adjoining the working element to move exactly to a desired location, in particular by means of the exact control of the linear and rotatively independent movement. The lifting movement and the swiveling movement can be activated independently of each other and, in particular, can be programmed. The same applies for the parameters of linear lift and rotational angle, linear acceleration and velocity and angular velocity and angular acceleration.
By means of the arrangement of the linear motors and of the rotative motors in the cylinder wall of the housing element, the greatest masses remain in the housing element. By this means, the working element is of very lightweight design and can therefore absorb relatively large accelerations and velocities and angular velocities. Furthermore, a system of this type operates in a virtually wear-free manner, since only the bearings, preferably designed as sliding bearings or as rolling contact bearings or as a combination of both bearings, are in engagement between housing element and working element.
It has proven particularly advantageous for the working element to be adjoined on the end side by a measuring device via a bearing element which sits in a sleeve-like manner on the working element.
The bearing element decouples a rotative movement between working element and measuring device, with the result that the latter is coupled only linearly to the working element. For this purpose, the measuring device is guided linearly, if appropriate via a guide element, so that a rotative movement of the measuring device is decoupled.
The linear movement of the measuring device can be read exactly via highly precise linear sensors, which are preferably assigned to the housing element on the inside and interact with, for example, magnetic strips of a measuring device, and by this means the path which is to be covered or has been covered and the linear acceleration and velocity can be determined exactly and highly precisely and controlled via the linear motor.
At the same time, by means of the rotative fixing of the measuring device relative to the working element by two rotation sensors spaced apart in a contactless manner with respect to each other on, on the one hand, the measuring device and, on the other hand, the working element, an exact determination of the rotational angle, of the number of revolutions, of the angular velocity and of the angular acceleration is possible. By this means, any desired angle or any desired number of revolutions can be read exactly and highly precisely controlled and programmed with the aid of the rotative motor.
By supporting the measuring device by means of at least one spring element relative to a base of a housing element, the dead weight of the working element can, in particular, be balanced and, if appropriate, if the current should fail damage to the working element falling downwards towards the base of the housing element can be prevented. The reduction in the dead weight enables the working element to move substantially more rapidly and more easily. Higher loads can be picked up or the dead weight and the size or the power of the linear motor can be reduced.
Furthermore, it is advantageous in the case of the present invention that the linear motor and rotative motor can be activated and supplied with power via the housing element via fixed, immobile connecting lines. The same applies to the linear sensor and to the rotative sensor.
All of the connections to the working element take place in a contactless manner without direct supply of power by means of cables, lines or the like.
This increases the service life of lifting/swiveling drives of this type, in particular. It is furthermore advantageous that the working element, which is designed, for example, as a hollow shaft, can be used in order to pass compressed air or negative pressure into a tool or a similar working device connected thereto. Lines of this type may correspondingly also be passed through, should this be desirable.